1. Field of the Invention
The present invention relates to a coordinates input device including a position appointing device having a superior maneuverability and capable of in putting coordinates data with a high degree of precision. More particularly, the present invention is concerned with a coordinates input apparatus capable of transmitting hand-written characters and patterns through, for example, a telephone network and capable of displaying characters and patterns which have been transmitted thereto.
2. Description of the Prior Art and its Problems
A coordinates input apparatus has heretofore been known having a magnetostrictive transmission medium, a position appointing device, a driving coil provided on one end of the magnetostrictive transmission medium or the pointing end of the position appointing device, and a detection coil provided on the pointing end of the position appointing device or one end of the magnetostrictive transmission medium, wherein a pulse current is supplied to the driving coil so as to generate a magnetostrictive vibration wave in the magnetostrictive transmission medium and the vibration wave propagating through the magnetostrictive transmission medium induces a voltage in the detection coil, whereby the position of the position appointing device is determined through processing the time interval between the application of the driving pulse current and the detection of the induced voltage by a suitable processing means.
In another known coordinates input apparatus, a plurality of driving lines and a plurality of detection lines are arranged orthogonally to each other thus forming a matrix. In operation, a position is detected by a position appointing apparatus having a magnetic member such as a ferrite, and driving current is supplied to the successive driving lines while the successive detection lines are scanned, whereby the appointed position is determined as the position on the detection line in which a specifically high voltage is induced.
The position detection apparatus of the first mentioned type exhibits a considerably high degree of position detection but undesirably requires a cord for exchange of timing signals between the position appointing device and the processing device and other portions of the apparatus. In consequence, the handling is undesirably restricted due to the presence of the cord. In addition, it is necessary that the position appointing device be held perpendicularly to the magnetostrictive transmission medium and in close proximity to the magnetostrictive transmission medium.
The second type of the apparatus is advantageous in that it can provide a cordless construction. Unfortunately, however, the resolution is determined by the pitch of the lines. For attaining a high resolution, it is necessary that the pitch of the lines be reduced. A smaller pitch of the lines, however, impairs the S/N ratio and the stability, so that a difficulty is encountered in the improvement in resolution. In addition, it is generally difficult to detect the positions right above the crossing points of the driving lines and the detection lines. It is also to be pointed out that the position appointing device has to be placed in the very close proximity of the lines. It has also been known to transmit pattern data through, for example, telephone networks. In such a case, the pattern data is transmitted either in the form of analog data through facsimile or after conversion into predetermined digital data through an image scanner and a personal computer, in the form of modulation/demodulation circuit (MODEM).
The facsimile and the image scanner, however, can read only the characters and patterns drawn or printed on a sheet, and there is no means for directly transmitting the hand-written letters and patterns or for deleting or correcting the content of the data. In addition, an impractically long time is required for the reading of the data.